Patent GB-250839-A (GB)
Title: Improvement in screw machines
IPC: B23B9/02
Filed: 1925-10-09
Abstract: 250,839. Hayden, G. D. Oct. 9, 1925. Lathes; feed motions.-In an automatic lathe for producing screws, pins &c., from bar stock, of the kind having a number of work spindles rotatable in a turret, a tool carriage is fed towards and from the work by a rack and two mutilated gear wheels rotating continuously at uniform speed in opposite directions, the termination and reversal of each stroke being produced by separate cam means. The tool carriage 35 has a rack 46, Fig. 10, engaged by the mutilated gears 47, 48, mounted on the oppositely rotating shafts 18, 33 connected by gears 31, 32, Fig. 1, and driven by worm-gearing and spur gearing 14 from an electric motor 9. The gears advance and retract the carriage at a high constant speed and as they pass out of gear with the rack at either end, pins on the carriage are engaged by cams 50, 53, Fig. 10, mounted on the shaft 18 which gradually bring the carriage to rest and then reverse it. In the forward position the tools remain at rest in contact with the work in order to reduce inaccuracies due to springing of the parts of the machine, and in the rearward position the work turret is indexed while the carriage remains stationary. Saddles.-The tools are mounted on the saddle 35, Fig. 9, by means of T-slots 37 and 40, the latter being symmetrically disposed with relation to the axis of rotation of the work-turret 57 and equidistant from the chucks 88. In a modification, the part 39 of the saddle has vertical sides in which the slots 40 are situated. An additional cross-saddle 4 is provided. Spindle mountings; turrets. - The workspindles 66 are mounted in bearings in two spiders 58, 60, Fig. 5, which form the turret, and are rotatable about a shaft 13 driven by gearing 11, Fig. 1, from the motor 9 and carrying a gear wheel 64, Fig. 5, engaging pinions 68 on the spindles to rotate them continuously. The bearings consist of bushes 74, 79, a radial ball bearing 78 and a thrust ball bearing 72. Axial movement of the spindles to the left is prevented by integral collars 67 and to the right by split nuts 82 adjusted through a hole in the turret-casing 57 and locked by bolts 83. The turret is indexed by providing the rear plate 59 with radial slots 102, Fig. 3, which are engaged by a pin 103 on an arm 104 attached to a cam 55 driven by bevel gearing from the shaft 18, any desired means being employed for locking the turret. Chucks.-Each chuck comprises a sleeve 89, Fig. 5, engaging at its forward end a collet 85 and actuated by levers 90 pivoted on a collar 92 on the spindle 66 and oscillated by a coned collar 94. Each collar 94 is grooved to engage an arcuate member 126, Fig. 1, attached to a slide 124 and reciprocated to actuate each chuck separately by means of a lever engaged by cam surfaces on the drum 55, the slide itself being attached to two similar levers mounted on pivots 110. The chuck jaws 86 each have a central nib 87, Fig. 15, which engages the bevelled cap 88, Fig. 5. Bar feeds.-The bar stock is fed by spring fingers 100, Fig. 5, reciprocated by a sleeve 96 having a grooved collar 97, each collar being engaged in turn by an arcuate member 119, Figs. 1 and 3, attached to a slide 115 carried by a second slide 114 which is reciprocated by a lever 120 actuated bv cam surfaces on the drum 55. The slide 114 is mounted on two similar levers 106 carried by pivots 110, and the slide 115 is actuated positively in the rearward direction by a pin 116 and yieldingly in the forward direction by a spring 117. Beds and frames.-The top of the bed 1 is formed flat and the side bosses, to which the brackets for supporting the shaft bearings &c. are attached, are formed in the same planes so that a number of beds mav be finished simultaneously on a planing machine at a single setting of the tool for each side and the top.